There are various forms of methods and equipment for measuring an angle defined by positions of components relative to each other, for example the positions of the wheels of a motor vehicle. One such method which operates on an optical principle and an apparatus for causing out the method are to be found for example in U.S. Pat. No. 3,337,961, in which connecting lines between sensors fixed to the vehicle wheels are identified by means of light beams.
Instead of an optical measuring method and apparatus, there are also wheel position measuring methods and apparatuses in which the connecting lines between sensors fixed to the vehicle wheels are identified by means of cords or lines, as for example in U.S. Pat. No. 3,164,910.
With modern measuring equipment, the signals supplied by the above-mentioned sensors are evaluated electronically, using a computer, and the corresponding angles or wheel positions are thus appropriately measured, as disclosed for example in U.S. Pat. Nos. 4,239,389 and 4,265,537.
Although the measuring methods and apparatuses which involve the use of cords or lines for ascertaining for example motor vehicle wheel positions can embrace relatively large angular ranges of .+-.45.degree. and more, the cords which identify the mechanical connecting lines between the sensors can give rise to difficulties. Such difficulties may be due to oscillations performed by the cords, while in addition the cords tend to suffer from friction and unintentional deflection effects. That can result in a hysteresis effect and under some circumstances may also result in measurement errors. Such apparatuses therefore require that the operating personnel carry out the method in an extremely careful fashion if the measurement results are not to be seriously falsified. While the cord-less or optical measuring methods and apparatuses do not suffer from the above-mentioned difficulties resulting from the mechanical considerations concerned with cords, such as hysteresis effect, frictional forces and unintentional deflection, the angular measurement range involved with such optical methods and apparatuses is extremely limited and in known equipment is only a maximum of .+-.10.degree.. It is therefore necessary to use additional sensors on turntables or the like in order to cover larger angular ranges, for example the maximum steering control deflection of the front wheels of a motor vehicle.